The present invention relates in general terms to indicating displays for motor vehicles, and more particularly to an indicating display which is equipped with a plurality of light sources which are aligned with each other, and all of which take part in a common indicating function.
An indicating display of the above general type, known in the current state of the art, comprises for example a plurality of light emitting diodes. This may for example consist of a raised stop lamp for fitting in a rear window or in a rearwardly facing part of a motor vehicle.
In order that such a display shall satisfy the photometric requirements imposed by current regulations, it includes, arranged in line with the light emitting diodes, an intermediate screen which is provided with Fresnel lenses, each of which is associated with a corresponding one of the diodes in order to concentrate the light in the axis of the vehicle, and a lens which receives light from the intermediate screen and which is provided with contoured elements for the horizontal and vertical distribution of the light. One drawback of this known solution lies in the fact that, because of the presence of the light sources, the intermediate screen and the lens, arranged one after another in a straight path, the indicating light unit has a substantial length in the direction of the optical axis.
This disadvantage is even more inconvenient in the case of raised stop lights which are fitted within the cabin of the vehicle. For a unit fitted in such a position, it is desirable that its size should be as small as possible.
A main object of the present invention is therefore to provide an indicating display having a shortened axial length.
According to the invention, an indicating display for a motor vehicle, of the type comprising a plurality of light sources aligned with each other, optical means for concentrating the light flux emitted by the sources into a general emission direction, and a lens which is provided with optical means for diffusing the light, is characterised in that the optical concentrating means consist of a mirror having a parabolic cross section delimited by two planes, both of which lie on the same side of its optical axis, and which extend in line with the lens, and in that the light sources are offset vertically with respect to the lens.
According to a preferred feature of the invention, the mirror is defined by a part of the housing.
Preferably, the light sources are situated substantially below the lens, in a cavity which is delimited by portions of the housing which extend the latter downwardly.
According to another preferred feature of the invention, the mirror consists of a plurality of portions of paraboloids of revolution, the foci of which lie substantially on the corresponding respective light sources.
Preferably, the light sources are light emitting diodes.
According to a further preferred feature of the invention, the housing includes two extensions having unequal lengths and extending from the upper and lower edges of the lens, the said extensions receiving at their free end a smooth transparent inclined cover plate.
Preferably, the light sources are oriented generally in a direction opposed to the exit direction of the light from the indicating display.
Further features, objects and advantages of the present invention will appear more clearly on a reading of the following detailed description of a preferred embodiment of the invention, which is given by way of example and with reference to the accompanying drawings.